The possibility of plant growth depends on different environmental factors such as temperature, humidity, and concentrations of salts in soil. In some cases, an environment characterized by such factors is suitable for a certain plant but not for other plants. In general, the above factors that would influence plant growth are referred to as environmental stresses. Cases in which a given plant cannot grow or can grow but with difficulty in an environment characterized by certain environmental stresses are explained by noting that the plant lacks environmental stress resistance. On the other hand, the ability of a plant to grow in an environment characterized by certain environmental stresses is explained by noting that such plant has environmental stress resistance.
If environmental stress resistance can be imparted to a plant, it becomes possible to expand the area in which the plant can be cultivated, allowing the effective use of limited ground space. In particular, an energy crop such as sugarcane is used as a raw material for biofuel. Therefore, it is desirable for such energy crop to gain resistance to a variety of environmental stresses. That is to say, if environmental stress resistance can be imparted to such an energy crop, the energy crop can be cultivated in an area in which the crop could not otherwise be cultivated due to the above described environmental factors.
As a technique for imparting environmental stress resistance to plants, for example, Patent Document 1 describes a known method for the overexpression of the Arabidopsis thaliana tyrosine phosphatase (PTP) gene (At3g44620). According to Patent Document 1, drought resistance can be imparted to plants by causing the overexpression of the PTP gene. Moreover, Non-patent Document 1 describes that the expression of the Arabidopsis thaliana-derived tyrosine phosphatase gene (At1g71860) is induced by high-salt treatment.